FastWoman

No, I didn't miss the check valve, but my brain was dozing and didn't recognize the significance. Pray tell, where did you find a check valve? Or did you figure out how to refurb the old one?

That's funny!

Before you start stripping apart the wiring harness, be warned that half/most of the wires are black -- with tiny little yellow numbers here and there! There are a few internal bullet connections that could be checked, and of course any modifications should be readily apparent. However, I doubt there's much you'll see. I think you missed the alternative test for the ECU I mentioned in my last post. It doesn't require cranking the engine. Starter issue: You might have an issue with bad switches (even the button that was added) or crusty connections. This is a somewhat common issue in the Z. It might be good to test the starter by jumping the solenoid's spade straight to the + post of the battery. I can't help you with pin 20 of the ECU. That pin is not used/connected in the '78. (It's probably not used in the '76 either.) On the '78, I see pins 35, 17, and 16 are the main ECU grounds. Although there are minor modifications between years, I suspect the same pins provide the ground in '76.

Our winter projects will be the completion of our new dock and the refitting of our sailboat. I'd love a warm garage for either of those! As soon as the weather clears, I'll be floating beneath the dock in a leaky little skiff, pulling wire. Your project list sounds exciting, Captain! Turbo motor?

I doubt you'd hear an intake leak. A small exhaust leak at the cylinder head would most likely produce a loud tap-tap-tap sound, like a valve gone bad, except without the chugging exhaust. My vote would be a belt squeak. Belts squeak the most when they're cold. Perhaps try some belt dressing?

Sounds like the battery is weak, so your cranking voltage is probably pretty low. I don't know that you can draw too many conclusions without normal voltage. Anyway, if you're not getting a full engine rotation per crank, the injectors are unlikely to fire. The ECU counts sparks from the ignition, firing the injectors on every third spark. Here's an alternative test: Connect up a wire to the (-) post of the coil, and leave the other end hanging. Plug in the Xmas tree lights. Turn the key to "ON." Now tap the wire to ground. Every three taps should give you a flash of the Xmas tree lights.

FAIW, I mounted that HEI module to the backside of a single, square, TO3 heatsink (like this one: Invalid Request ), using two mounting screws on opposite corners. (I think I had to enlarge them slightly to get the right spacing.) And then I mounted the heatsink/HEI assembly to my driver-side fender using the same two screw holes as the distributor pickup junction block (which I removed). The spacing was perfect, and there was just enough clearance between the fins and the hood. Best of all, this is a relatively cool part of the engine compartment. PS I can identify much too well with your 70's era parts collection.

Sorry, Kris, the advertising links had me confused! Grrrr....

I think you're getting ahead of yourself. I thought you had replaced the fuel injection relay (that powers the ECU), not the fuel pump relay (that powers the fuel pump). A running fuel pump vs. an operating ECU are separate issues. Unlike with many EFI systems, the ECU does NOT control the fuel pump in any way. So you need to trace fuel pressure issues separately. I wonder whether you bought the right type of relay. If the old relay will actuate the fuel pump, then it's almost certainly working properly. Furthermore, you would have no other wiring issues. Perhaps you plugged a fuel injection relay into the fuel pump relay connector? (I don't know whether the plug configuration looks similar. It's very different on the '78.) In diagnosing the system, remember that the fuel pump should only run with the key in the START position, not the RUN position, unless the engine is actually running. If you prop the AFM's vane open and turn the key to ON, I believe the pump should run. Diagnosing the EFI is a completely different ball of yarn. To verify injector pulses, pull out a miniature Xmas light bulb ('tis the season!), and plug it into an injector connector. It should flash dimly as you crank the engine -- once per engine rotation. If you unplug the coolant temp sensor, it should flash longer/brighter. To diagnose the EFI, you should download the "Fuel Injection Bible" for the 280Z.

Silly Northahnah, salt is for delicious, deep-fried foods, not roads! Y'all need to move down to a gentler climate, Captain! The ugly weather here will come and go. We're expecting about 3" of rain here in VA. Then we'll be off to Richmond in my Z for T'giving with family. The Z is our preferred road car.

I don't know the '76 that well. Each year was a little different, with different safety mechanisms used to shut off the fuel pump if the engine stopped running. I believe the '76 still used a switch inside the airflow meter. When the engine draws air, the vane opens, and the fuel pump switch closes. Then of course there's the main fuel pump relay. The most common electrical problem these cars have is crusty connections. For starters, I'd recommend pulling off all the connectors, cleaning them up, dabbing with a bit of dielectric grease, and reassembling. Then I'd focus in on the connectors that might be problematic with the fuel pump system. Check the big connector to the airflow meter and the one to the fuel pump relay. As you're checking out the FP relay connector, keep in mind that you can short across two of the connectors to deliver power to the fuel pump. I don't know whether the color codes are different on the '76 (re the '78, which is the year I have), but the wires feeding the pump are blue/green. If you short these connectors and the fuel pump fires up, you either have a bad relay or a crusty relay connection. If the pump doesn't fire up, then you've got a connection problem elsewhere. Of course confirm that you've really got +12 on one of the connectors you're shorting! If you've got 12V to the relay and no joy with the short, then I'd say check the following: 1. There are two huge connectors for the wiring harness just inside the passenger firewall, at least on my '78. The FP circuit runs through one of the connectors. Make certain the connector isn't crusty/burnt. Mine was burnt (really an inadequate contact for the circuit), so I snipped it out and used a bullet connector. 2. Check the integrity of the contacts on the pump. 3. Check the integrity of the ground, which runs back through the floor to somewhere in the hatch area -- in the toolboxes, I think.

Willoughby, are you saying the Nissan Sentra IM will work in the Z? (I imagine it would.) Do you have a pinout or wiring diagram? I prefer the look of the connector on the Sentra module to the unprotected pins of GM's HEI. I looked up the 280Z specifically and didn't see an ignition module. I did see a service whereby for a mere $275 a company called Jet would reprogram the PROM (programmable read only memory) chips on our analog ECUs (which don't have PROM chips!).

What Zed said! However, just to clarify, when he says to pull the hose off the FPR, he means the little vacuum hose on top, not one of the fuel hoses. The spec pressure is something like 36.3 psi, but your gauge might not be dead-on accurate, especially if you bought a cheapo gauge like I did. (Mine actually cross-checks with other gauges I have, though.) Also it's interesting that he mentioned the low 20's or less, as that's approx. the point my engine would run noticeably badly when my fuel pump was fading.

A SUDDEN dropout of power doesn't sound like the fuel pump. If your pump suddenly stopped pumping, your power would fade over maybe 1-5 seconds, depending on whether your engine is under load. SUDDEN dropouts of power sound more like ignition to me. Adding to this hunch is the fact that your tach sometimes reads zero. You might have a weak/fading ignition that is only barely adequate to trigger the tach and that sometimes drops out. Also remember that the ECU is triggered by the ignition. If the ignition pulse is so weak your tach can't read it, it might be so weak your ECU can't read it either. In that case your fuel delivery would suddenly drop out, as the ECU wouldn't put out any injector pulses. If I were you, I'd check over the ignition system. The problem would be a low-voltage one -- somewhere from the ignition module to the ignition coil, but not beyond. It might also be in the wiring from the (-) post of the coil to the ECU and tach. Sometimes our ignition modules fade away. Mine did. You can either install a "refurbished" unit (meaning that they cleaned it up, I think), or you can retrofit with something else. I did a GM HEI retrofit on my car, which was quite cheap ($11 for the chip, plus some wire). It continues to work very well. You can search for that mod on this forum.

The fuel line between the filter and the fuel rail is 8mm. You'll find 5/16" fuel line at the auto parts store, and that's almost exactly the same. You'll need fuel injection rated hose -- approx. $4/ft, as I recall. (Don't buy the cheap stuff for carbureted systems, lest you have your pretty Z burst into flames someday from a fuel line rupture.) FYI, there's a very nice looking fuel injection hose that's black, with a thin, blue inner wall. I would recommend you avoid it, as it easily becomes delaminated.

Congrats on the new AFM! You might not be running as rich as you think. I don't know how old you are, but many people have no memory of cars prior to catalytic converters. Exhaust nowadays is almost odorless -- not somewhat gassy, like back in the day. That said, plugs should read about the same as they always have. If your plugs look sooty, then you're running rich. The insulators ideally should be a nice, light shade of mocha -- not black (rich) or chalky white (lean). If your engine is running rich, the most likely culprit is a faulty connection to the coolant temp sensor. Those connectors in the thermo housing area take a lot of abuse. The best place to check the resistance of the coolant temp sensor circuit is right at the ECU connector, as that will tell you whether you have any faulty connections. (Or sometimes some clever mechanic might have inserted a resistor inline with the CTS wiring and wrapped it up in the harness, making the mixture richer -- as was the case in my car.) Like the wheels!

Well, you could always put your car on a dyno, but that's expensive! My only tricks when test driving a questionable vehicle are the obvious: Stay very close to home, and have someone available by telephone to come and pick you up if your car quits on you. Carry your tools with you. If possible, do a lot of test driving in an empty nearby parking lot. Churches are great for this. When you get a bit braver and want to extend your range, an AAA card with unlimited towing is a must! I'd say it's a must for any classic car owner, regardless. You never know when these old machines are going to exhibit personality.

I've often said a car that's been sitting can suffer from "cobwebs" that clear once the car is driven regularly. This same concept is embodied in the "Italian tuneup" (running the @#$% out of the engine to blow out all the whatever). Anyway, maybe your engine is suffering somewhat from cobwebs. Idling the engine, even at a high idle, is not equivalent to actually driving it, at least for purposes of determining whether your fuel/air ratio is right. That's because the engine isn't under load and isn't sucking in nearly as much fuel and air. Shifting through the gears while sitting in the driveway probably does nothing of any use.

If you watch ebay and are patient, you'll probably catch one there. I picked up a spare ECU for my '78 for a cool $20. You can also buy a "remanufactured" one for around $250, but I doubt "remanufacturing" amounts to much more than cleaning it and making it look pretty.

^^^ When asked on Thanksgiving what I'm thankful for, I'll be able to say Lenny is burning the midnight oil to give my Z digital fuel injection!

De nada, mi amigo!

I'd put it this way: If you're actually going to drive and enjoy the car, it probably makes little difference whether it's a 240 or 280. Pick the car you prefer. If you're going to make a lot of modifications to the car, it's probably better you choose a 280, because there are more of them. (It's a good karma thing.) You can make a 280 quite a bit like a 240, except a tad sturdier and with a bigger engine, if that's what you want. If you're going to keep the car bone-stock, restore it to showroom condition, and drag it around to car shows on a trailer, the 240 will be a somewhat better investment.

Oh, I might mention the '75 was my first Z. It has by far the prettiest EFI engine, IMO. The only thing I don't like about it is the airflow meter, which lacks the backfire valve on the metering vane that was part of the design in all the other years. I *think* you can substitute a '76 AFM. The problem with the '75 AFM is that a bad backfire will bend the vane. That will happen even with a backfire valve, but not as badly. Another thing both the '75 and '76 lack is the hood vents and heat shields. Heat soaking of the fuel rail system is a known issue in these cars, and the vents and shields really help with hot restarts.

IMO, the 240 might be a (slightly) better car to collect or to race, but the 280 is a better car for ordinary driving. Put back in proper shape, the 280 is a very reliable and comfortable (quieter, more refined) machine. Besides that, I think it looks cooler with the floating front bumper. The 240 is more of a sports car, and the 280 is more of a GT. IMO the biggest difference between the models is EFI vs. carburation. If you like carburation (I don't), the 240 might be your machine. Of course you can put carbs on a 280, but I think it's a pity when that happens. FAIW, NEITHER model will be a good investment if you're the one doing the restoration. The best advice anyone ever gave me (and many people have said it) is to buy a car that someone else has dumped tons of money into -- a car that is as close to the condition that you want. I would modify that advice slightly to say that there should be some deficit in the car you buy that is not, by itself, an enormous or costly project. That will give you the chance to bond with the car. (I know it might be weird, but I never really bonded with any car before taking a wrench to it.) BTW, for an alternative EFI, check out the ZFuel thread in the Fuel Injection forum. A more modern, turn-key EFI might be soon at hand.

You're both quite welcome. I hope it all comes out well! FAIW, siteunseen, although a patch into the wiring harness with a couple of bullet connectors is the least invasive way to add the potentiometer, snipping the #13 wire (as I recall) of the EFI harness and inserting the potentiometer there (under the dash) is perhaps the "better" way. (See towards the end of the thread I linked.) This will keep the potentiometer in a cleaner, cooler environment, where it is likely to be more stable. Good luck with your engines, guys! :-)